lint-staged

.eslintrc

@@ -1,4 +1,5 @@
 {
+  "parser": "babel-eslint",
   "parserOptions": {
     "ecmaVersion": "2018"
   },

.flowconfig

@@ -0,0 +1,11 @@
+[ignore]
+
+[include]
+
+[libs]
+
+[lints]
+
+[options]
+
+[strict]

.lintstagedrc

@@ -0,0 +1,11 @@
+{
+  "linters": {
+    "*.js": [
+      "eslint"
+    ],
+    "*.+(js|jsx|json|yml|yaml|css|less|scss|ts|tsx|md|graphql|mdx)": [
+      "prettier --write",
+      "git add"
+    ]
+  }
+}

package.json

@@ -5,14 +5,22 @@
   "main": "index.js",
   "scripts": {
     "lint": "eslint src",
-    "format": "prettier --write \"**/*.+(js|jsx|json|yml|yaml|css|less|scss|ts|tsx|md|graphql|mdx)\""
+    "flow": "flow",
+    "format": "npm run prettier -- --write",
+    "prettier": "prettier \"**/*.+(js|jsx|json|yml|yaml|css|less|scss|ts|tsx|md|graphql|mdx)\"",
+    "validate": "npm run lint && npm run prettier -- --list-different && npm run flow",
+    "precommit": "lint-staged && npm run flow"
   },
   "keywords": [],
   "author": "Kent C. Dodds <kent@doddsfamily.us> (http://kentcdodds.com/)",
   "license": "MIT",
   "devDependencies": {
+    "babel-eslint": "^9.0.0",
     "eslint": "^5.5.0",
     "eslint-config-prettier": "^3.0.1",
+    "flow-bin": "^0.81.0",
+    "husky": "^0.14.3",
+    "lint-staged": "^7.2.2",
     "prettier": "^1.14.2"
   }
 }

src/example.js

@@ -7,5 +7,4 @@ if (!('serviceWorker' in navigator)) {
 
 const greeting = 'hello'
 console.log(`${greeting} world!`)
-
 ;[(1, 2, 3)].forEach(x => console.log(x))

src/flow-example.js

@@ -0,0 +1,22 @@
+// @flow
+function add(a: number, b: number): number {
+  return a + b
+}
+
+type User = {
+  name: {
+    first: string,
+    middle: string,
+    last: string,
+  },
+}
+function getFullName(user: User): string {
+  const {
+    name: {first, middle, last},
+  } = user
+  return [first, middle, last].filter(Boolean).join('')
+}
+
+add(1, 2)
+
+getFullName({name: {first: 'Joe', middle: 'Bud', last: 'Matthews'}})